Endoscope tip cover and endoscope

ABSTRACT

An endoscope distal end cover (10) is a cover for protecting a distal end (20t) of an endoscope (20) which has an observation window at the distal end, including: a synthetic polymer film (13) which is to be located over the observation window (32) when the endoscope distal end cover is attached to the distal end of the endoscope, wherein the synthetic polymer film has a surface which includes a plurality of raised portions, when viewed in a normal direction of the synthetic polymer film, a two-dimensional size of the plurality of raised portions is in the range of more than 20 nm and less than 500 nm, and a static contact angle of water with respect to the surface is not less than 98°.

TECHNICAL FIELD

The present invention relates to an endoscope distal end cover forprotecting the distal end of endoscopes (including rigid and flexibleendoscopes), an endoscope including an endoscope distal end cover, and amethod for using an endoscope distal end cover.

BACKGROUND ART

An antireflection technique which has been receiving attention in recentyears is forming over a substrate surface a microscopic uneven patternin which the interval of recessed portions or raised portions is notmore than the wavelength of visible light (λ=380 nm to 780 nm). SeePatent Document No. 1 and Patent Document No. 2. The two-dimensionalsize of a raised portion of an uneven pattern which performs anantireflection function is not less than 10 nm and less than 500 nm.Here, the “two-dimensional size” of the raised portions refers to thearea equivalent circle diameter of the raised portions viewed in adirection normal to the surface. For example, when the raised portionshave a conical shape, the two-dimensional size of the raised portions isequivalent to the diameter of the base of the cone. The same applies tothe “two-dimensional size” of the recessed portions.

The present applicant conceived a method for producing an antireflectionfilm (an antireflection surface) which has a moth-eye structure with theuse of an anodized porous alumina layer. Using the anodized porousalumina layer enables manufacture of a mold which has an invertedmoth-eye structure with high mass-productivity (see, for example, PatentDocuments No. 1 through No. 4). The entire disclosures of PatentDocuments No. 1 through No. 4 are incorporated by reference in thisspecification.

The present applicant developed the above-described technology andarrived at a synthetic polymer film whose surface has a microbicidaleffect (see, for example, Patent Document No. 5). The entire disclosuresof Patent Document No. 5 are incorporated by reference in thisspecification.

The present applicant discloses an optical film which has excellentantireflection properties and has excellent anti-smear properties andabrasion resistance in Patent Document No. 6, and films which haveexcellent anti-smear properties in Patent Documents No. 7 and No. 8. Theentire disclosures of Patent Documents No. 6 through No. 8 areincorporated by reference in this specification.

However, when blood or body fluid is adhered to an observation window ofan endoscope, disadvantageously, the field of view for observationcannot be maintained. Endoscopes presently used include, for example, amechanism for washing the observation window. Washing of the observationwindow is realized by washing away the blood or the like adhered to theobservation window with a washer liquid ejected from a nozzle providedat the distal end of the endoscope. The washer liquid adhered to theobservation window is removed by air blown out of the nozzle.

CITATION LIST Patent Literature

-   Patent Document No. 1: Japanese Patent No. 4265729-   Patent Document No. 2: Japanese Laid-Open Patent Publication No.    2009-166502-   Patent Document No. 3: WO 2011/125486-   Patent Document No. 4: WO 2013/183576-   Patent Document No. 5: WO 2015/163018 (Japanese Patent No. 5788128)-   Patent Document No. 6: WO 2016/174893 (Japanese Patent No. 5951165)-   Patent Document No. 7: WO 2018/012340-   Patent Document No. 8: WO 2018/012342

SUMMARY OF INVENTION Technical Problem

However, even if an endoscope used has the above-described washingmechanism, washing the observation window takes time (washing cannot becompleted within a short time). Further, washing sometimes causes blood(and a washer liquid contaminated with blood) to spread over theobservation window so that observation can be difficult. When theobservation window is not cleaned by washing, it is necessary to oncepull the distal end of the endoscope out of a body cavity.

An object of the present invention is to provide an endoscope distal endcover and an endoscope in which adhesion of blood or body fluid to theobservation window of the endoscope is suppressed and the observationwindow can be kept clean or easily washed as compared with theconventional systems.

Solution to Problem

According to an embodiment of the present invention, solutions describedin the following Items are provided.

[Item 1]

An endoscope distal end cover for protecting a distal end of anendoscope which has an observation window at the distal end, comprising:

a synthetic polymer film which is to be located over the observationwindow when the endoscope distal end cover is attached to the distal endof the endoscope,

wherein the synthetic polymer film has a surface which includes aplurality of raised portions,

when viewed in a normal direction of the synthetic polymer film, atwo-dimensional size of the plurality of raised portions is in the rangeof more than 20 nm and less than 500 nm, and

a static contact angle of water with respect to the surface is not lessthan 98°.

[Item 2]

The endoscope distal end cover of Item 1, wherein the static contactangle of water with respect to the surface of the synthetic polymer filmis not less than 128°. The static contact angle of hexadecane withrespect to the surface is preferably not less than 35°.

[Item 3]

The endoscope distal end cover of Item 1 or 2, further comprising aliquid film of a water-repellent oil covering a surface of at least aportion of the synthetic polymer film located on the observation window.

[Item 4]

The endoscope distal end cover of Item 3, wherein the water-repellentoil is a silicone oil or a fluoric oil.

[Item 5]

The endoscope distal end cover of Item 3 or 4, wherein thewater-repellent oil is a silicone oil whose kinematic viscosity is lowerthan 350 mm²/s.

[Item 6]

The endoscope distal end cover of Item 3 or 4, wherein thewater-repellent oil is a silicone oil whose kinematic viscosity is equalto or lower than 10 mm²/s.

[Item 7]

The endoscope distal end cover of any of Items 1 to 6, wherein thesynthetic polymer film includes a resin film which is made of aphotocurable resin.

[Item 8]

The endoscope distal end cover of Item 7, wherein the synthetic polymerfilm further includes a water-repellent and oil-repellent layer formedon the resin film.

[Item 9]

The endoscope distal end cover of Item 7 or 8, wherein the photocurableresin contains a first polymerizable fluoric compound which contains afluorine element, the first polymerizable fluoric compound has aplurality of polymerizable functional groups and has a molecular weightof not less than 1000 and not more than 5000, and at the lapse of 5minutes since placing a 200 μL drop of water on the surface of thesynthetic polymer film, a pH of an aqueous solution is not less than 6.5and not more than 7.5.

[Item 10]

The endoscope distal end cover of Item 9, wherein

the photocurable resin contains a photopolymerization initiator, and

the photopolymerization initiator contains at least one of the groupconsisting ofethanone,1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl]-,1-(C)-acetyloxime),2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]phenyl}-2-methyl-propan-1-one,and 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propane-1-one.

[Item 11]

The endoscope distal end cover of Item 9 or 10, wherein

the photocurable resin further contains a second polymerizable fluoriccompound which contains a fluorine element, and

the second polymerizable fluoric compound is a monofunctionalpolymerizable compound and has a molecular weight of not less than 100and not more than 1000.

[Item 12]

The endoscope distal end cover of any of Items 9 to 11, wherein aproportion of the first polymerizable fluoric compound to thephotocurable resin is not less than 1 mass % and not more than 5 mass %.

[Item 13]

An endoscope comprising the endoscope distal end cover as set forth inany of Items 1 to 12, the endoscope distal end cover being attached tothe endoscope.

Advantageous Effects of Invention

According to an embodiment of the present invention, an endoscope distalend cover, an endoscope and a method for using an endoscope distal endcover are provided in which adhesion of blood or body fluid to theobservation window of the endoscope is suppressed and the observationwindow can be kept clean or easily washed as compared with theconventional systems.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1(a) is a schematic diagram of an endoscope system 100 whichincludes an endoscope 20 of an embodiment of the present invention. FIG.1(b) is a schematic diagram of an endoscope distal end cover 10 of anembodiment of the present invention.

FIG. 2(a) and FIG. 2(b) are schematic cross-sectional views of syntheticpolymer films 13A and 13B, respectively, which are suitably used in theendoscope distal end cover 10 of an embodiment of the present invention.

FIG. 3(a), FIG. 3(b) and FIG. 3(c) are cross-sectional viewsschematically showing endoscope distal end covers 10A, 10B and 10C,respectively, of an embodiment of the present invention.

FIG. 4(a), FIG. 4(b) and FIG. 4(c) are cross-sectional viewsschematically showing endoscope distal end covers 10D, 10E and 10F,respectively, of an embodiment of the present invention.

FIG. 5(a) and FIG. 5(b) are cross-sectional views schematically showingstates of the endoscope distal end cover 10C of an embodiment of thepresent invention and an attachment 22 attached thereto.

FIG. 6(a), FIG. 6(b) and FIG. 6(c) are schematic diagrams showing an endface of the distal end of endoscopes 20A, 20B and 20C, respectively, ofan embodiment of the present invention.

FIG. 7(a), FIG. 7(b) and FIG. 7(c) are diagrams schematically showingstates of a film for use in an endoscope distal end cover of anotherembodiment of the present invention where a water-repellent oil isapplied to a surface of the film.

DESCRIPTION OF EMBODIMENTS

Hereinafter, the configurations of an endoscope distal end cover, anendoscope, and a method for using an endoscope distal end coveraccording to an embodiment of the present invention are described withreference to the drawings. The endoscope distal end cover and theendoscope according to an embodiment of the present invention are notlimited to those illustrated in the following paragraphs.

FIG. 1(a) is a schematic diagram of an endoscope system 100 whichincludes an endoscope 20 of an embodiment of the present invention. FIG.1(b) is a schematic diagram of an endoscope distal end cover 10 of anembodiment of the present invention.

The endoscope 20 described herein is an endoscope for use inlaparoscopic surgery, although the endoscope distal end cover of anembodiment of the present invention is not limited to illustratedendoscopes but widely applicable to endoscopes with an observationwindow at the distal end.

For example, after a trocar (insertion device) 42 is pierced into a bodycavity from the abdominal surface of a patient, the insertion section 20a of the endoscope 20 is inserted into the body cavity through thetrocar 42, and various treatments are performed while the inside of thebody cavity is displayed on a monitor. The control section 20 b of theendoscope 20 is connected to a computer and a light source unit via auniversal cable and is capable of various operations, includingilluminating, photographing, operation of a forceps (not shown), supplyof a washer liquid or washer gas through a gas/liquid supply tube 54,etc. An insufflation gas (carbon dioxide gas) is supplied into anabdominal cavity through an insufflation tube 56 connected with thetrocar 42. The trocar 42 has a valve 44. The valve 44 is to prevent theinsufflation gas from leaking out of the opening of the trocar 42.

The end face of the endoscope distal end 20 t includes, for example, anobservation window 32, illumination windows 34 a, 34 b, a forcepsopening 36 and an ejection nozzle as shown in FIG. 6(a). The observationwindow 32 is washed by ejecting a washer liquid and/or compressed airfrom the ejection nozzle 38 onto the observation window 32. However, aspreviously described, washing the observation window takes time (washingcannot be completed within a short time). Further, washing sometimescauses blood (and a washer liquid contaminated with blood) to spreadover the observation window so that observation can be difficult. Whenthe observation window is not cleaned by washing, it is necessary toonce pull the distal end of the endoscope out of a body cavity.

When the endoscope distal end cover 10 of an embodiment of the presentinvention is attached to the endoscope distal end 20 t, adhesion ofblood or body fluid to the observation window 32 of the endoscope 20 issuppressed so that the observation window can be kept clean as comparedwith the conventional systems.

As shown in FIG. 1(b), the endoscope distal end cover 10 (hereinafter,also simply referred to as “cover”) includes a synthetic polymer film 13which is to be located over the observation window when the endoscopedistal end cover 10 is attached to the endoscope distal end 20 t. Thesynthetic polymer film 13 has a surface which includes a plurality ofraised portions. When viewed in a normal direction of the syntheticpolymer film 13, the two-dimensional size of the plurality of raisedportions is in the range of more than 20 nm and less than 500 nm. Thestatic contact angle of water with respect to the surface is not lessthan 150°. The static contact angle of hexadecane with respect to thesurface is not less than 60°. That is, the synthetic polymer film 13 hasa moth-eye structure over the surface and exhibits excellent waterrepellency and excellent oil repellency, so that adhesion of blood orbody fluid can be suppressed. Even if there is blood or the like adheredto the surface of the synthetic polymer film 13, the surface can becleaned more easily and more assuredly than the conventional systems.The moth-eye structure produces an antireflection function (for example,reflectance of 0.2% or less) and, therefore, a large amount of light canbe guided to the observation window as compared with the conventionalsystems.

The cover 10 includes, for example, a synthetic polymer film 13, a basefilm 12 provided on the endoscope 20 side of the synthetic polymer film13, and a cover member 16 provided on the endoscope 20 side of the basefilm 12 as shown in FIG. 1(b). The synthetic polymer film 13 is formedfrom, for example, a photocurable resin. The synthetic polymer film 13and the base film 12 are provided only over the end face of the distalend 20 t. The cover member 16 has greater tensile elongation than thebase film 12 and is also provided on the lateral surface of the distalend 20 t. The base film 12 and the synthetic polymer film 13 provided onthe base film 12 constitute a film 14 which has a moth-eye structureover the surface.

The synthetic polymer film 13 that has the moth-eye structure at thesurface is preferably formed from a photocurable resin as will bedescribed later. Therefore, the synthetic polymer film 13 has relativelypoor stretchability. As will be described later, in order to form thesynthetic polymer film 13 according to a roll-to-roll method, using asthe base film 12 a film which is relatively stiff, i.e., a film whichhas relatively high elastic modulus (e.g., PET, TAC, PC), is preferred.In such a case, it is difficult to directly cover the endoscope distalend 20 t with the film 14 that has the moth-eye structure. Particularly,it is difficult to bring the film 14 into close contact with the endface such that no air gap is present between the film 14 and theobservation window 32.

In view of the foregoing, the cover member 16 provided has greatertensile elongation than the base film 12, and the distal end 20 t iscovered with the cover member 16. The tensile elongation (elongation atbreak in tensile test: ASTM D638) of the cover member 16 is preferablynot less than 100%, more preferably not less than 200%, still morepreferably not less than 300%. The cover member 16 may be, for example,a film whose thickness is not more than 500 μm (see, for example, FIG.3(a) and FIG. 3(b)). Alternatively, the cover member 16 may have theshape of a cap covering the endoscope distal end 20 t (the shape of ahollow cylinder with one end being closed) (see FIG. 3(c)).

The cover member 16 and the film 14 (base film 12) are joined togetherby, for example, an adhesive layer 15. When the cover member 16 and thefilm 14 can be thermally welded together, the adhesive layer 15 may beomitted. As a matter of course, the cover member 16 preferably has hightransmittance for visible light. The transmittance for visible light ofthe cover member 16 is preferably not less than 80%, more preferably notless than 90%.

Examples of the polymer material suitably used for the cover member 16include acrylic elastomers, olefin elastomers, styrene elastomers, vinylchloride elastomers, ester elastomers, fluoroelastomers, and siliconeelastomers (silicone rubber). When a film is used as the cover member16, not only the aforementioned elastomers but also acrylic resins,polyolefin resins, polystyrene resins, vinyl chloride resins, polyesterresins, fluororesins and silicone resins, whose elongation is smallerthan those of the elastomers, can also be used. When athermally-shrinkable film is used among these resins, the cover member(cover film) 16 can be easily brought into close contact with theendoscope distal end 20 t. Herein, “olefin” includes polyethylene,polypropylene, and copolymers of ethylene and α-olefin (propylene,butene, hexene, octene, 4-methylpentene, etc.).

The cover member 16 preferably has high transparency for visible light.The transparency for visible light is preferably not less than 80%, morepreferably not less than 90%. From the viewpoint of transparency,acrylic, polypropylene, styrene, vinyl chloride and polyester materialsare preferred.

The method of securing the cover member 16 to the endoscope distal end20 t after the cover member 16 is attached to the endoscope distal end20 t is not particularly limited. For example, the cover member 16 maybe secured to the distal end 20 t using a stretchable medical tape.Alternatively, an adhesive agent (including a pressure sensitiveadhesive) may be used. Further, a securing member may be used whichincludes a cylindrical attaching member capable of pressing the covermember 16 against the lateral surface of the distal end 20 t when thecover member 16 is attached to the endoscope distal end 20 t (see, forexample, FIG. 4(a), FIG. 4(b) and FIG. 4(c)). As a matter of course, aplurality of securing methods may be used in combination.

Next, the configuration of the synthetic polymer film 13 is describedwith reference to FIG. 2(a) and FIG. 2(b).

FIG. 2(a) and FIG. 2(b) are schematic cross-sectional views of syntheticpolymer films 13A and 13B, respectively, which are suitably used in theendoscope distal end cover 10. The synthetic polymer films 13A and 13Billustrated herein are provided on base films 12A and 12B, respectively.

A film 14A shown in FIG. 2(a) includes a base film 12A and a syntheticpolymer film 13A provided on the base film 12A. The synthetic polymerfilm 13A has a plurality of raised portions 13Ap over its surface. Theplurality of raised portions 13Ap constitute a moth-eye structure. Whenviewed in a normal direction of the synthetic polymer film 13A, thetwo-dimensional size of the raised portions 13Ap, D_(p), is in the rangeof more than 20 nm and less than 500 nm. Here, the “two-dimensionalsize” of the raised portions 13Ap refers to the diameter of a circleequivalent to the area of the raised portions 13Ap when viewed in anormal direction of the surface. When the raised portions 13Ap have aconical shape, for example, the two-dimensional size of the raisedportions 13Ap is equivalent to the diameter of the base of the cone. Thetypical adjoining distance of the raised portions 13Ap, D_(int), is morethan 20 nm and not more than 1000 nm. When the raised portions 13Ap aredensely arranged so that there is no gap between adjoining raisedportions 13Ap (e.g., the bases of the cones partially overlap eachother) as shown in FIG. 2(a), the two-dimensional size of the raisedportions 13Ap, D_(p), is equal to the adjoining distance D_(int). Thetypical height of the raised portions 13Ap, D_(h), is not less than 50nm and less than 500 nm. The height D_(h) of the raised portions 13Apmay be not more than 150 nm. The thickness of the synthetic polymer film13A, t_(s), is not particularly limited but only needs to be greaterthan the height D_(h) of the raised portions 13Ap.

The synthetic polymer film 13A shown in FIG. 2(a) has the same moth-eyestructure as the antireflection films disclosed in Patent Documents No.1 through No. 4. From the viewpoint of producing an antireflectionfunction, it is preferred that the surface has no flat portion, and theraised portions 13Ap are densely arranged over the surface. Further, theraised portions 13Ap preferably has a such shape that thecross-sectional area (a cross section parallel to a plane which isorthogonal to an incoming light ray, e.g., a cross section parallel tothe surface of the base film 12A) increases from the air side to thebase film 12A side, e.g., a conical shape. From the viewpoint ofsuppressing interference of light, it is preferred that the raisedportions 13Ap are arranged without regularity, preferably randomly.Furthermore, the uneven structure of the synthetic polymer film 13Aproduces a so-called Lotus effect and therefore exhibits excellent waterrepellency and excellent oil repellency.

A film 14B shown in FIG. 2(b) includes a base film 12B and a syntheticpolymer film 13B provided on the base film 12B. The synthetic polymerfilm 13B has a plurality of raised portions 13Bp over its surface. Theplurality of raised portions 13Bp constitute a moth-eye structure. Inthe film 14B, the configuration of the raised portions 13Bp of thesynthetic polymer film 13B is different from that of the raised portions13Ap of the synthetic polymer film 13A of the film 14A. Descriptions offeatures which are common with those of the film 14A are sometimesomitted.

When viewed in a normal direction of the synthetic polymer film 13B, thetwo-dimensional size of the raised portions 13Bp, D_(p), is in the rangeof more than 20 nm and less than 500 nm. The typical adjoining distanceof the raised portions 13Bp, D_(int), is more than 20 nm and not morethan 1000 nm, and D_(p)<D_(int) holds. That is, in the synthetic polymerfilm 13B, there is a flat portion between adjoining raised portions13Bp. The raised portions 13Bp have the shape of a cylinder with aconical portion on the air side. The typical height of the raisedportions 13Bp, D_(h), is not less than 50 nm and less than 500 nm. Theraised portions 13Bp may be arranged regularly or may be arrangedirregularly. When the raised portions 13Bp are arranged regularly,D_(int) also represents the period of the arrangement. This also appliesto the synthetic polymer film 13A, as a matter of course.

In this specification, the “moth-eye structure” includes not onlysurficial nanostructures that have an excellent antireflection functionand that are formed by raised portions which have such a shape that thecross-sectional area (a cross section parallel to the film surface)increases as do the raised portions 13Ap of the synthetic polymer film13A shown in FIG. 2(a) but also surficial nanostructures that are formedby raised portions which have a part where the cross-sectional area (across section parallel to the film surface) is constant as do the raisedportions 13Bp of the synthetic polymer film 13B shown in FIG. 2(b). Notethat, however, the tip of the conical portion may be rounded.

As disclosed in Patent Document No. 5, the synthetic polymer film mayfurther have a plurality of second raised portions which aresuperimposedly formed over a plurality of first raised portions. Herein,raised portions of the above-described synthetic polymer film which havea two-dimensional size in the range of more than 20 nm and less than 500nm are referred to as “first raised portions”. The two-dimensional sizeof the second raised portions is smaller than the two-dimensional sizeof the first raised portions and does not exceed 100 nm.

A mold for forming the moth-eye structure such as illustrated in FIG.2(a) and FIG. 2(b) over the surface (hereinafter, referred to as“moth-eye mold”) has an inverted moth-eye structure obtained byinverting the moth-eye structure. Using an anodized porous alumina layerwhich has the inverted moth-eye structure as a mold without anymodification enables inexpensive production of the moth-eye structure.Particularly when a moth-eye mold in the shape of a hollow cylinder isused, the moth-eye structure can be efficiently manufactured accordingto a roll-to-roll method. Such a moth-eye mold can be manufacturedaccording to methods disclosed in Patent Documents No. 2 through No. 5.That is, by alternately and repeatedly performing the anodization stepand the etching step on an aluminum film deposited on a base or on analuminum base through multiple cycles, a moth-eye mold is obtained whichincludes a porous alumina layer which has an inverted moth-eyestructure.

The surface of the synthetic polymer film 13 has the moth-eye structureobtained by inverting the surficial nanostructure of the moth-eye mold.According to the surficial nanostructure of the moth-eye mold used, thesynthetic polymer films 13A and 13B shown in FIG. 2(a) and FIG. 2(b),respectively, can be produced. The material that forms the syntheticpolymer film 13 is not limited to the UV-curable resin but may be aphotocurable resin which is curable by visible light.

[Synthetic Polymer Film]

Sample films which had the same configuration as the film 14A shown inFIG. 2(a) were produced using UV-curable resins of differentcompositions. The materials used in the UV-curable resins for productionof the synthetic polymer films of respective sample films are shown inTABLE 1.

TABLE 1 Water Number EO MATE- Abbrevi- Product Manufacturer Solu- EO ofmoles mass RIALS ation Name Name Compound Name Remarks bility group MWof EO % Monomer M280 M280 MIWON polyethylene glycol YES YES 508 9 78(400) diacrylate M282 M282 MIWON polyethylene glycol YES YES 308 4 57(200) diacrylate VEEA VEEA NIPPON 2-(2-vinyloxy ethoxy) YES YES 200 2 44SHOKUBAI ethyl acrylate CO., LTD. ACMO ACMO KJ ChemicalsN,N-acryloylmorpholine YES NO  99 — — Corporation UA UA-510H KYOEISHAdipentaerythritol — — — — — CHEMICAL pentaacrylate Co., LTD.hexamethylene diisocyanate urethane prepolymer ATM ATM- Shin Nakamuraethoxylated — — — — — 35E Chemical pentaerythritol Co., Ltd.tetraacrylate DPE LIGHT KYOEISHA dipentaerythritol — — — — — ACRYLATECHEMICAL hexaacrylate DPE-6A Co., LTD. DM DMAA KJ Chemicals dimethylacrylamide — — — — — Corporation ATMM A-TMM- Shin Nakamurapentaerythritol NO NO — — — 3LMN 3LM-N Chemical triacrylate Co., Ltd.Anti- MT70 FOMBLIN ® SOLVAY perfluoropolyether polymerizable, NO unknown3000  smear MT70 derivative; 80% tetrafunctional Agent methyl ethylketone used after — — — — — (solvent); 20% substituted with ACMO FAAC6CHEMINOX UNIMATEC 2-(perfluorohexyl)ethyl polymerizable NO NO 418 FAAC-6Co., Ltd. acrylate DAC OPTOOL DAIKIN modified polymerizable — — — — —DAC-HP INDUSTRIES, perfluoropolyether LTD. (PFPE) DL100 POEM RIKENdiglycerol — unknown — — — DL-100 VITAMIN Co., monolaurate Ltd. (fattyacid ester) Polymer- OXE02 IRGACURE BASF ethanone,1-[9-ethyl- — — — — —ization OXE02 6-(2-methyl benzoyl)- Initiator 9H-carbazole-3-yl]-,1-(O-acetyl oxime) 2959 Omnirad IGM Resins 1-[4-(2-hydroxyethoxy)- — — —— — 2959 phenyl]-2-hydroxy-2- methy1-1-propane-1-one 819 IRGACURE IGMResins bis(2,4,6-trimethyl- 819 benzoyl)-phenyl- phosphine oxide TPOIRGACURE IGM Resins diphenyl(2,4,6-trimethyl- — — — — — TPO benzoyl)phosphine oxide

As the synthetic polymer film, for example, the synthetic polymer filmdisclosed in Patent Document No. 8 can be used. The blend of thematerials used in the UV-curable resin for formation of the syntheticpolymer film of Example 1 is shown in TABLE 2. TABLE 3 shows theevaluation results of the film surface (the surface of the syntheticpolymer film). Example 1 corresponds to Example 1 disclosed in PatentDocument No. 8. The evaluation method is the same as that employed inExample 2 and Example 3 which will be described later.

TABLE 2 Anti- Polymerization smear Monomer Initiator Agent UA ATM DPE DMACMO 819 DAC Example 1 8.0% 45.0% 18.5% 24.0% 1.5% 2.0% 1.0%

TABLE 3 Film Surface Properties Water Hexadecane Contact Angle ContactAngle (°) (°) Immediately Immediately Adhesion After Dropped AfterDropped 10 sec Example 1 Excellent 158.0 66.0 31.0

The synthetic polymer film of Example 1 contains a polymerizable fluoriccompound as the anti-smear agent. DAC-HP (manufactured by DAIKININDUSTRIES, LTD.) used herein has two polymerizable functional groups.The molecular weight is 1169 to 1999, and the proportion of thecontained fluorine element is 24.4 mass % to 42.8 mass % (all thesenumbers are estimates). The synthetic polymer film of Example 1 has avery high static contact angle of water, 158.0°, and hasultrahydrophobicity. The synthetic polymer film of Example 1 has a veryhigh static contact angle of hexadecane, 66.0°, and has excellent oilrepellency.

[Improvement of Synthetic Polymer Film]

According to research conducted by the present inventors, it was foundthat a conventional synthetic polymer film such as disclosed in PatentDocument No. 8 sometimes changed the pH of water (aqueous solution)adhered to the surface of the film. Since the diameter of the endoscopedistal end cover is not more than about 10 mm, it is estimated that theinfluence on a human body or the like is small, but it is preferred thatit does not affect the pH. In view of such, the present inventorsstudied a synthetic polymer film of which the water repellency and oilrepellency are further improved and which less affects the pH of water(aqueous solution) adhered to the surface of the film.

As a result, the present inventors found that, when a synthetic polymerfilm 13 which has the above-described surface structure is producedusing a photocurable resin which contains a polymerizable fluoriccompound which has a plurality of polymerizable functional groups, thesurface of the resultant synthetic polymer film has further improvedwater repellency and oil repellency, and the influence on the pH ofwater (aqueous solution) on the surface is small. It was also foundthat, when the photocurable resin further contains a monofunctionalpolymerizable fluoric compound, the resultant synthetic polymer film canhave further improved water repellency and oil repellency.

Some of the polymerization initiators produce an organic acid throughphotodecomposition (e.g., 819). To further reduce the influence on thepH of water (aqueous solution) adhered to the surface, using apolymerization initiator which does not produce an organic acid throughphotodecomposition is preferred. As the polymerization initiator whichdoes not produce an organic acid, not only OXE02:ethanone,1-[9-ethyl-6-(2-methyl benzoyl)-9H-carbazole-3-yl]-,1-(O-acetyloxime) and 2959:1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propane-1-one butalso, for example, Omnirad 127 (IGM Resins):2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]phenyl}-2-methyl-propan-1-onecan be suitably used. These polymerization initiators, advantageously,do not cause coloring or emission of a smell.

The small influence on the pH of water (aqueous solution) on the surfacemeans that, for example, at the lapse of 5 minutes since placing a 200μL drop of water on the surface of the synthetic polymer film, the pH ofthe aqueous solution is not less than 6.5 and not more than 7.5. Asynthetic polymer film which has such characteristics is disclosed inJapanese Laid-Open Patent Publication No. 2019-156879 of the presentapplicant. The entire disclosure of Japanese Laid-Open PatentPublication No. 2019-156879 is incorporated by reference in thisspecification.

Of the “Anti-smear Agents” shown in TABLE 1, MT70 and FAAC6 contain afluorine element and are polymerizable. Anti-smear agent MT70 has aplurality of polymerizable functional groups. That is, MT70 is apolyfunctional polymerizable fluoric compound. MT70 has a urethanemethacrylate group. The number of polymerizable functional groupsincluded in MT70 is four. The molecular weight (MW) of MT70 in TABLE 1represents the weight average molecular weight measured by GPC with acalibration with polystyrene standards.

Anti-smear agent FAAC6 is a monofunctional polymerizable fluoriccompound. That is, FAAC6 has one polymerizable functional group. Thechemical structural formula of FAAC6 is shown at [CHEMICAL FORMULA 1].

As the sample film which includes a base film 12A and a syntheticpolymer film 13A provided on the base film 12A, Example 2 and Example 3were produced. The blend composition of the materials of the respectivesynthetic polymer films and the type of the base film are shown in TABLE4.

As the base film 12A, a 50 μm thick PET (polyethylene terephthalate)film (“A4300” manufactured by TOYOBO CO., LTD.), an 80 μm thick TAC(triacetyl cellulose) film (“TAC-TD80U” manufactured by FUJIFILM) or a110 μm thick PC (polycarbonate) film (“Iupilon KS3410UR” manufactured byMitsubishi Engineering-Plastics Corporation (Iupilon is a registeredtrademark)) was used.

Each of the sample films was produced using a moth-eye mold through thefollowing process.

For the moth-eye mold, an aluminum film (thickness: about 1 μm) wasformed on a glass substrate (about 5 cm×about 5 cm), and anodization andetching were alternately and repeatedly performed on this aluminum film,whereby a porous alumina layer (D_(p): about 200 nm, D_(int): about 200nm, D_(h): about 150 nm) was formed. Since the porous alumina layer hasa structure obtained by inverting the moth-eye structure of thesynthetic polymer film 13A, corresponding parameters which define thedimensions may sometimes be designated by the same symbols. Thereafter,a mold releasing treatment (also referred to as “die releasingtreatment”) was performed on the surface of the moth-eye mold (thesurface which has the inverted moth-eye structure). The die releasingtreatment broadly includes the treatment of applying a mold releasingagent to a surface of a die (herein, the surface of the moth-eye mold).Herein, a fluoric mold releasing agent (OPTOOL DSX (modifiedperfluoropolyether (PFPE)) manufactured by DAIKIN INDUSTRIES, LTD) wasused as the mold releasing agent and was applied to the surface of themoth-eye mold by an immersion method. Note that four types of fluoricmold releasing agents were used, which contain a fluoric mold releasingcomponent and a fluoric solvent with different mold releasing componentconcentrations. The standard concentration was 0.1%, low concentration Iwas 0.001%, low concentration II was 0.0001%, and low concentration IIIwas 0.00001%. In either case, the concentration was represented inmassa. Commercially-available OPTOOL DSX has an effective componentconcentration of 20% and diluted with a fluoric solvent (perfluorohexaneor the like) to a predetermined concentration when used. In dilution forthe concentration adjustment, a fluoric solvent manufactured by FluoroTechnology (product name: diluent ZV) was used. As will be describedlater with experimental examples, the water repellency and oilrepellency of the surface of the synthetic polymer film can be adjustedby treating the surface of the moth-eye mold with mold releasing agentsof different concentrations.

The UV-curable resin applied to the surface of the base film 12A wasirradiated with ultraviolet light (UV) with the moth-eye mold beingpressed against the base film 12A, whereby the UV-curable resin wascured. Thereafter, the moth-eye mold was separated from the base film12A, whereby a synthetic polymer film 13A to which the inverted moth-eyestructure of the moth-eye mold was transferred was formed on the surfaceof the base film 12A. The exposure amount was about 200 mJ/cm² (on thebasis of light at the wavelength of 375 nm). In each sample film, D_(p)was about 200 nm, D_(int) was about 200 nm, and D_(h) was about 150 nm.In each sample, the synthetic polymer film was produced without using asolvent. In the ultraviolet light irradiation, a UV lamp manufactured byFusion UV Systems (product name: LIGHT HANMAR6J6P3) was used.

When the PC film was used as the base film 12A (Example 3), a UV-curableresin was applied to the moth-eye mold while the moth-eye mold washeated to 20° C. or 40° C. on a heat stage. On the moth-eye mold towhich the UV-curable resin was applied, the PC film was placed andevenly pressed against the mold using a hand roller. Then, theUV-curable resin was irradiated with ultraviolet light from the PC filmside so as to be cured, whereby the sample film including the syntheticpolymer film on the PC film was obtained. The process of producing thesynthetic polymer film on the PC film is also referred to as “transferprocess”. The temperature in that process (20° C. or 40° C.) is alsoreferred to as “transfer temperature”.

TABLE 4 Polymerization Anti-smear Monomer Initiator Agent Base M280 M282VEEA ACMO OXE02 2959 MT70 FAAC6 Film Example 2 28.0% 62.6% 2.8% 1.9%1.9% 2.8% TAC Example 3 56.1% 37.4% 1.9% 1.9% 2.8% PC

The evaluation results of respective sample films of Example 2 andExample 3 as to the properties of the sample films, the adhesion betweenthe synthetic polymer film and the base film, and the properties of thesurfaces of the sample films (i.e., the surfaces of the syntheticpolymer films) are shown in TABLE 5A. Note that the films of Example 2and Example 3 shown in TABLE 5A were produced by performing theabove-described die releasing treatment using the mold releasing agentof the standard concentration. Sample films produced by performing thedie releasing treatment carried out in production of a synthetic polymerfilm which had the same composition as Example 2 with the use of themold releasing agent of low concentrations I, II and III were alsosubjected to the same evaluations, and the evaluation results are shownbelow in TABLE 5B. In TABLE 5B, Examples 2A, 2B and 2C are sample filmsproduced using the mold releasing agent of low concentrations I, II andIII, respectively.

For the properties of the sample films, evaluation of coloring and smellof the sample films and identification of acid were carried out. Theevaluated surface properties of the sample films were the spreadabilityof a water drop over the surface of the synthetic polymer film, thechange of the pH of the water drop, and the static contact angle ofwater or hexadecane with respect to the surface.

[Evaluation of Sample Film Properties]

Coloring

Coloring of the sample films (the degree of yellowing) was visuallyobserved.

∘: Transparent with no color even when 10 sheets of the sample film werestacked up;

Δ: Single sheet was transparent with no color, but yellowed portionswere detected when 10 sheets of the sample film were stacked up;

x: Yellowed portions were detected in a single sheet of the sample film.

Herein, when ∘ or Δ, the sample film was judged to be usable.

Smell

The presence/absence (degree) of a smell of the sample films wasevaluated as follows. A 5 cm×5 cm piece of the sample films was placedin a 100 mL glass container. The container was tightly closed and leftin an incubator at 40° C. for 24 hours. After being left for 24 hours,five panelists smelled and evaluated the degree of the smell in thecontainer immediately after the container was opened.

∘: Panelists noticed a faint smell, but the smell was not unpleasant;

Δ: Panelists noticed a smell, but the smell was not unpleasant;

x: Panelists noticed an unpleasant smell.

Herein, when ∘ or Δ, the sample film was judged to be usable.

[Evaluation of Adhesion to Base Film]

The adhesion of the synthetic polymer film to the base film wasevaluated as described in the following paragraph.

In an environment where the temperature was 23° C. and the humidity was50%, 11 vertical incisions and 11 horizontal incisions were formed in asurface of a synthetic polymer film of each sample film (a surfaceopposite to the base) using a utility knife at intervals of 1 mm in theshape of a grid such that 100 squares (1 mm on each side) were formed.Then, a polyester adhesive tape “No. 31B” manufactured by NITTO DENKOCORPORATION was placed on and pressed against the square portions.Thereafter, the adhesive tape was peeled off in a direction of 90° withrespect to the surface of the square portions at a velocity of 100 mm/s.Thereafter, the surface state of the synthetic polymer film on the basewas visually observed, and the number of squares from which the polymerlayer on the base was not removed, M, was counted. When the PC film wasused as the base film (Example 3), the evaluation was carried out atboth transfer temperatures, 20° C. and 40° C., and the same results wereobtained (the number of M was “100”).

[Evaluation of Film Surface Properties]

Degree of Spread of Water Over Synthetic Polymer Film

Deionized water was adjusted to pH=7.0±0.1 using 0.01 mol/L hydrochloricacid solution and 0.011 mol/L sodium hydroxide solution. That is,neutral water was prepared in this way.

On the surface of each sample film, a 0.2 cc (200 μL) drop of theabove-described pH-adjusted water was placed using a micropipette.Thereafter, the maximum spread diameter (area equivalent circlediameter) up to 5 min was measured, and the average value for fivemeasurements from each sample film was evaluated.

pH Measurement

The measurement of the pH was carried out as follows.

In the same way as that described above, on the surface of each samplefilm, a 0.2 cc (200 μL) drop of the above-described pH-adjusted waterwas placed using a micropipette. After the passage of 5 minutes, theaqueous solution (including water in which an extract from the syntheticpolymer film was dissolved) on the surface of each sample film wasmeasured using an electrode for flat samples which is described below,and the average value for five measurements from each sample film wasevaluated (Method 1). Method 2 is different from Method 1 in that theabove-described aqueous solution on the surface of each sample film wasscooped up using a sampling sheet for measurement. Unless otherwisespecified, Method 1 was used.

Electrode: pH electrode, product number: 0040-10D (semiconductor sensor)manufactured by HORIBA, Ltd.

Sampling sheet: sampling sheet B, product number: Y011A manufactured byHORIBA, Ltd.

Measurement of Static Contact Angle

The static contact angle of water and hexadecane with respect to thesurface of the synthetic polymer film of each sample film was measuredusing a contact angle meter (PCA-1 manufactured by Kyowa InterfaceScience Co., Ltd). A drop of water or hexadecane (about 10 μL) wasplaced on the surface of the synthetic polymer film of each sample film.The static contact angle was measured at the lapse of 1 second, 10seconds and 60 seconds since placing the water drop. The contact anglewas measured at three locations by a θ/2 method (θ/2=arctan (h/r), θ:contact angle, r: radius of liquid drop, h: height of liquid drop), andthe measurements at the three locations were averaged. Herein, the firstmeasurement location was at a central portion of each sample film. Thesecond and third measurement locations were away from the firstmeasurement location by 20 mm or more and were in point symmetry withrespect to the first measurement location. When the contact angle is notless than 150°, a liquid drop which was formed at the tip of amicrosyringe and brought into contact with the surface sometimes failedto land on (move onto) the surface, i.e., remained at the tip of amicrosyringe, so that the contact angle was unmeasurable. Such a casewas indicated as “not landed”. That is, “not landed” means that thecontact angle was not less than 150°.

TABLE 5A Film Surface Properties Water Hexadecane Water Contact AngleContact Angle Film Properties Diameter pH (°) (°) Adhesion Color Smell(mm) Method 1 Method 2 1 sec 10 sec 1 sec 10 sec Example 2 100 Δ ◯ 8.06.8 6.9 not landed 100.8 100.7 Example 3 100 ◯ ◯ 8.5 6.8 6.8 not landed100.1 99.8

See the evaluation results of the sample films of Example 2 and Example3 shown in TABLE 5A. Each of the curable resins for production of thesynthetic polymer films of Example 2 and Example 3 includes apolyfunctional polymerizable fluoric compound. Each of Example 2 andExample 3 has excellent water repellency (the static contact angle ofwater is not less than 150°) and exerts a small influence on the pH ofwater (aqueous solution) on the surface. Further, each of Example 2 andExample 3 has excellent oil repellency (the static contact angle ofhexadecane is not less than 100°).

The synthetic polymer films of Example 2 and Example 3 containanti-smear agent MT70 and anti-smear agent FAAC6. The sample film ofExample 2 includes a TAC film as the base film. In contrast, the samplefilm of Example 3 includes a PC film as the base film.

As disclosed in Japanese Laid-Open Patent Publication No. 2019-51638 ofthe present applicant, the present applicant found that a 2-(2-vinyloxyethoxy)ethyl (meth)acrylate monomer was a promising candidate for theacrylic monomer which can improve adhesion with a PC film. The entiredisclosures of Japanese Laid-Open Patent Publication No. 2019-51638 areincorporated by reference in this specification. If the proportion of a2-(2-vinyloxy ethoxy)ethyl (meth)acrylate monomer unit contained in thecross-linked structure of a synthetic polymer film to the entirety ofthe synthetic polymer film is, for example, not less than 15 mass % andless than 45 massa, the synthetic polymer film can have excellent PCadhesion. PC is a resin which generally exhibits high physicalproperties among engineering plastics and has been widely usedparticularly because of its excellent shock resistance and heatresistance.

In Example 3, VEEA manufactured by NIPPON SHOKUBAI CO., LTD. was used asthe 2-(2-vinyloxy ethoxy)ethyl acrylate, and polymerization initiator2959 was used. Example 3 has excellent adhesion with a PC film. Notethat Example 2 in which a TAC film was used as the base film hasacceptable adhesion with a TAC film.

The other examples of the PC film than those used in the above-describedexamples include “CARBOGLASS (registered trademark)” manufactured by AGCInc., “PUREACE (registered trademark)” manufactured by TEIJIN LIMITED,and “Makrofol (registered trademark)” manufactured by Covestro.

In the foregoing, an example of a multilayer film including apolycarbonate film and a synthetic polymer film wherein thepolycarbonate film was used as the base film has been described,although the present invention is not limited to this example. Forexample, a plastic molded product of polycarbonate can be used as theplastic base. In this case, a moth-eye mold may be used which ismanufactured using an aluminum film deposited on a glass base of adesired shape.

By laminating a molded product of various shapes with a multilayer filmwhich includes a polycarbonate film and a synthetic polymer film,excellent water repellency and excellent oil repellency can be given tothe surface of the molded product of various shapes, and a surface canbe realized which exerts a small influence on the pH of water (aqueoussolution) on the surface.

As illustrated with the experimental examples, when a synthetic polymerfilm is formed from a curable resin which contains a polymerizablefluoric compound which has a plurality of polymerizable functionalgroups, the synthetic polymer film can have excellent water repellencyand excellent oil repellency. Such a synthetic polymer film is alsoexcellent in durability of the water repellency and oil repellency atthe surface.

The polymerizable fluoric compound which has polymerizable functionalgroups includes, for example, a fluorine-containing hydrocarbon chainand a (meth)acrylate group at the terminal. The fluorine-containinghydrocarbon chain is likely to reside near the surface of curable resin.A synthetic polymer film which is realized by curing such a curableresin has excellent water repellency and excellent oil repellency.

Refer to the evaluation results of the sample films of Examples 2A, 2Band 2C shown in TABLE 5B. As the concentration of the mold releasingagent used in the die releasing treatment decreases, the waterrepellency decreases, although each of the sample films has excellentwater repellency and excellent oil repellency. When the surface of themoth-eye mold is treated with a fluoric mold releasing agent, theproportion of the fluorine element contained near the surface of thesynthetic polymer film can further increase. Thus, such a treatment ismore preferred from the viewpoint of excellent water repellency andexcellent oil repellency. The water repellency and oil repellency of thesynthetic polymer film can be adjusted by adjusting the concentration ofthe mold releasing agent. For achieving excellent water repellency andexcellent oil repellency, it is preferred that the concentration of themold releasing agent is, for example, not less than 0.001% (Example 2A).

TABLE 5B Film Surface Properties Water Hexadecane Water Contact AngleContact Angle Film Properties Diameter pH (°) (°) Adhesion Color Smell(mm) Method 1 Method 2 1 sec 10 sec 1 sec 10 sec Example 2A 100 Δ ◯ 8.16.8 6.8 128.1 127.6 64.3 35.1 Example 2B 100 Δ ◯ 8.3 6.8 6.9 101.2 98.531.4 15.3 Example 2C 100 Δ ◯ 8.3 6.8 6.9 94.3 89.6 19.6 10.1

In order that the polyfunctional polymerizable fluoric compound exhibitsexcellent water repellency and excellent oil repellency, it is preferredthat the length (volume) of the fluorine-containing hydrocarbon chainhas an appropriate size. If the length (volume) of thefluorine-containing hydrocarbon chain is excessively large, it issometimes difficult for the fluorine-containing hydrocarbon chain tomove to the vicinity of the surface of the synthetic polymer film. Asillustrated with the experimental examples, this problem can be solvedby using together a monofunctional polymerizable fluoric compound whichhas a relatively lower molecular weight. If the length (volume) of thefluorine-containing hydrocarbon chain is excessively large, thesolubility of the polymerizable fluoric compound to the other monomersof the curable resin decreases, and curing the curable resin sometimesresults in a whitened synthetic polymer film.

For example, it is preferred that the polyfunctional polymerizablefluoric compound has a molecular weight of not less than 1000 and notmore than 5000 and the proportion of the fluorine element contained inthe polyfunctional polymerizable fluoric compound is not less than 20mass % and not more than 60 massa. The molecular weight of thepolyfunctional polymerizable fluoric compound is more preferably notless than 2000 and not more than 4000, and the proportion of thefluorine element contained in the polyfunctional polymerizable fluoriccompound is more preferably not less than 30 mass % and not more than 50massa. A polyfunctional polymerizable fluoric compound which has arelatively large molecular weight such as described above preferably hastwo, three or four polymerizable functional groups, for example.

Examples of the polyfunctional polymerizable fluoric compound, otherthan those used in the above-described examples, include “AD1700”manufactured by SOLVAY, “Y-1200” and “X-71-1203M” manufactured byShin-Etsu Chemical Co., Ltd., “MEGAFACE RS-72-K”, “MEGAFACE RS-75”,“MEGAFACE RS-76-E”, “MEGAFACE RS-76-NS” and “MEGAFACE RS-77”manufactured by DIC Corporation, and “EBECRYL8110” manufactured byDAICEL-ALLNEX LTD.

For example, “AD1700” manufactured by SOLVAY is poly(tetrafluoroethyleneoxide-co-difluoromethylene oxide) with four functional groups at theterminal. The weight average molecular weight measured by GPC with acalibration with polystyrene standards is 3,500.

As illustrated with the experimental examples, when the curable resinused for formation of the synthetic polymer film further contains amonofunctional polymerizable fluoric compound, the synthetic polymerfilm can have more excellent water repellency and more excellent oilrepellency. It is preferred that the molecular weight of themonofunctional polymerizable fluoric compound is not less than 100 andnot more than 1000 and the proportion of the fluorine element containedin the monofunctional polymerizable fluoric compound is not less than 40mass % and not more than 70 massa. It is more preferred that themolecular weight of the monofunctional polymerizable fluoric compound isnot less than 300 and not more than 500. It is more preferred that theproportion of fluorine contained in the monofunctional polymerizablefluoric compound is not less than 50 mass % and not more than 60 mass %.

Examples of the monofunctional polymerizable fluoric compound, otherthan those used in the above-described examples, include “CHEMINOXFAMAC-4” and “CHEMINOX FAMAC-6” manufactured by UNIMATEC Co., Ltd. andProduct ID “C8ACRY”, “C8MTCRY”, “C10ACRY” and “C10MTCRY” manufactured byExfluor Research Corporation.

In the experimental examples, the polymerizable fluoric compound isreferred to as “anti-smear agent”, although the present invention is notlimited to this example. A fluoric compound which meets theabove-described conditions may be used.

The thus-produced synthetic polymer films of the above-describedembodiments have a surface which is excellent in water repellency andoil repellency and exerts a small influence on the pH of water (aqueoussolution) on the surface. Further, the synthetic polymer films have anantireflection function (for example, reflectance of 0.2% or less) and,therefore, a large amount of light can be guided to the observationwindow as compared with the conventional systems.

Since the surface of the above-described synthetic polymer film isexcellent in water repellency and oil repellency, adhesion of blood andbody fluid to the surface is suppressed. An example of the experimentalresults is shown below.

In the experiment, the following sample films were used:

Example Film 1 and Example Film 2 with the moth-eye surface, which wererespectively produced using the UV-curable resins of Example 2 andExample 3 described above and using PET as the base;

Comparative Example Film 1 and Comparative Example Film 2 without themoth-eye surface (i.e., with a flat surface), which were respectivelyproduced using the UV-curable resins of Example 2 and Example 3described above and using PET as the base;

Comparative Example Film 3 with the moth-eye surface and ComparativeExample Film 4 without the moth-eye surface (i.e., with a flat surface),which were respectively produced using the UV-curable resin ofComparative Example 1 whose composition is shown in TABLE 6 below andusing PET as the base;

Comparative Example Film 5 with the moth-eye surface, which was producedusing the UV-curable resin of Comparative Example 2 whose composition isshown in TABLE 6 below and using PET as the base; and

Comparative Example Film 6 which was the PET film itself.

The UV-curable resins of Comparative Example 1 and Comparative Example 2were hydrophilic. The static contact angle of water with respect toComparative Example Film 3 and Comparative Example Film 5 that had themoth-eye surface was less than 90°. The static contact angle ofhexadecane with respect to Comparative Example Film 3 and ComparativeExample Film 5 that had the moth-eye surface was less than 60°.

TABLE 6 Mold Releasing Monomer Initiator Agent Base UA7100 M280 M282ACMO ATMM3LMN OXE02 819 TPO DL100 Film Comparative 47.5% 47.5% 2.9% 1.0%1.0% PET Example 1 Comparative 50.3% 29.1% 17.7% 1.5% 1.5% PET Example 2

Example Film 1 and Example Film 2 and Comparative Example Film 1 throughComparative Example Film 6 were evaluated as to adhesion of blood.Herein, sheep blood (whole blood) was used instead of human blood.Adhesion of the sheep blood to the surfaces of the synthetic polymerfilms were evaluated as described below.

[Test Method]

1. Each film was placed such that the surface faces upward with a slantof about 20°.

2. One 15 μL drop of sheep whole blood was dropped from above the film,and it was checked whether the blood flows down to the lower part of thefilm or stays on the film.

3. The procedure of Step 2 was repeated five times in the same way, andit was counted how many times the blood stayed on the film.

4. 1-2 mL PBS (phosphate buffered saline) was poured over the drop ofthe blood, and the washability was evaluated.

The evaluation results are shown in TABLE 7A below.

TABLE 7A Number of adhered Sample Films Material Surface Shape drops/5drops PBS Washing Example Film 1 Example 2 moth-eye 2 Blood was cleanlywashed away. Comparative flat 5 Unclear mixture of Example Film 1 waterand blood spread. Example Film 2 Example 3 moth-eye 1 Blood was cleanlywashed away. Comparative flat 5 Unclear mixture of Example Film 2 waterand blood spread. Comparative Comparative moth-eye 5 Unclear mixture ofExample Film 3 Example 1 water and blood spread. Comparative flat 5Unclear mixture of Example Film 4 water and blood spread but wassomewhat flowable. Comparative Comparative moth-eye 5 Unclear mixture ofExample Film 5 Example 2 water and blood spread. Comparative PET flat 5Unclear mixture of Example Film 6 water and blood spread.

As seen from the results shown above, in Example Film 1 and Example Film2, the blood was unlikely to adhere, and the blood was easily washedaway. That is, when the contact angle of water with respect to themoth-eye surface was not less than 150° and the contact angle ofhexadecane with respect to the moth-eye surface was not less than 100°,the sheep blood hardly adhered to the surface and was easily washedaway.

As seen from the results of Comparative Example Film 1 and ComparativeExample Film 2, on the surface without the moth-eye structure, thewasher liquid (PBS) and the blood were mixed together and not easilywashed away. On Comparative Example Film 3 through Comparative ExampleFilm 5 that have hydrophilic surfaces, the washer liquid and the bloodwere mixed together and not easily washed away even when the surfaceshad the moth-eye structure. Also, on Comparative Example Film 6 that isa PET film, the washer liquid and the blood were mixed together and noteasily washed away.

Next, the evaluation results of the sample films of Examples 2A, 2B and2C are shown below in TABLE 7B.

TABLE 7B Number of adhered Sample Films Material Surface Shape drops/5drops PBS Washing Example Film 1A Example 2A moth-eye 3 Blood wascleanly washed away. Comparative Example 2B moth-eye 5 Unclear mixtureof Example Film 1B water and blood remained and adhered. ComparativeExample 2C moth-eye 5 Unclear mixture of Example Film 1C water and bloodremained and adhered.

As seen from the results shown above, for achieving an excellent bloodadhesion suppressing effect, it is preferred that the concentration ofthe mold releasing agent is, for example, not less than 0.001% (Example2A). Specifically, a synthetic polymer film with a surface where thecontact angle of water (at the lapse of 10 seconds since the landing ofthe drop) with respect to the surface is not less than 128° and thecontact angle of hexadecane (at the lapse of 10 seconds since thelanding of the drop) with respect to the surface is not less than 35°can produce an excellent blood adhesion suppressing effect (see TABLE5B). Note that the sample films of Example 2 and Example 3 which havebeen described in the foregoing section have extremely high waterrepellency and oil repellency so that the contact angle of water was notable to be measured. As for the contact angle of hexadecane, nosignificant difference was found between the value measured at the lapseof 1 second since the landing of the drop and the value measured at thelapse of 10 seconds since the landing of the drop, although the contactangle usually decreases with the passage of time. Therefore, when thecontact angle changes over time, it is preferred from the viewpoint ofreproducibility or the like that the value measured at the lapse of 10seconds since the landing of the drop is used as the index.

Next, specific configuration examples of the endoscope distal end coverof an embodiment of the present invention are described with referenceto FIG. 3 through FIG. 6. As a matter of course, the endoscope distalend cover of an embodiment of the present invention is not limited tothose illustrated below.

FIG. 3(a), FIG. 3(b) and FIG. 3(c) are cross-sectional viewsschematically showing endoscope distal end covers 10A, 10B and 10C,respectively, of embodiments of the present invention.

The endoscope distal end cover 10A shown in FIG. 3(a) includes asynthetic polymer film 13, a base film 12 provided on the endoscope 20side of the synthetic polymer film 13, and a cover film 16 provided onthe endoscope 20 side of the base film 12, which serves as the covermember 16. The base film 12 and the synthetic polymer film 13 providedon the base film 12 constitute a film 14 which has a moth-eye structureover the surface.

The cover film 16 has greater tensile elongation than the base film 12.For example, the tensile elongation of the cover film 16 is preferablynot less than 100%, more preferably not less than 200%, and still morepreferably not less than 300%. The cover film 16 of high flexibility isin close contact with the end face of the endoscope distal end 20 t (seeFIG. 1(b)) and is arranged so as to cover the distal end 20 t. Thethickness of the cover film 16 is, for example, not more than 500 μm andis preferably not more than 300 μm. The thickness does not have aparticular lower limit but is preferably not less than 100 μm inconsideration of strength and/or handleability.

The base film 12 and the cover film 16 are bonded together using, forexample, a known adhesive agent for optical purposes (adhesive layer15). The refractive index of the adhesive layer 15 is preferably closeto those of the base film 12 and the cover film 16. As a matter ofcourse, the adhesive layer 15 is preferably transparent. Thetransmittance for visible light of the adhesive layer 15 is preferablynot less than 80%, more preferably not less than 90%.

The cover film 16 that is arranged so as to cover the endoscope distalend 20 t is secured at the lateral surface of the distal end 20 t using,for example, a stretchable medical tape (not shown). In this case, toprevent a body fluid or blood from entering through a gap between thecover film 16 and the endoscope distal end 20 t, the edge of the coverfilm 16 is assuredly covered with the medical tape, and the medical tapeis assuredly adhered to the lateral surface of the endoscope distal end20 t.

The endoscope distal end cover 10B shown in FIG. 3(b) also includes acover film 16 as the cover member 16 as does the endoscope distal endcover 10A. The cover 10B further includes an adhesive layer 17 which isprovided on the endoscope side of the cover film 16 in the cover 10A.The adhesive layer 17 is provided only over the end face of theendoscope distal end 20 t as is the film 14 that has the moth-eyestructure at the surface. As a matter of course, in some types of theendoscope 20, the adhesive layer 17 has an opening corresponding to theopenings 10Fa or 10Ga as shown in FIG. 6(a) and FIG. 6(b).

The adhesive layer 17 is preferably made of a relatively-soft adhesiveagent (including a pressure sensitive adhesive) for improving theadhesion to the endoscope distal end 20 t. For example, an elasticadhesive agent which exhibits rubber elasticity when cured and anadhesive agent which has a closed cell structure (see, for example,Japanese Patent No. 6066390) can be used. When a relatively-softadhesive agent is used, the adhesive agent can cover steps in the endface of the endoscope distal end 20 t, so that the absence of air gaps(bubbles) between the adhesive layer 17 and the end face of theendoscope distal end 20 t can be readily realized.

The cover member 16 of the endoscope distal end cover 10C shown in FIG.3(c) has the shape of a cap (the shape of a hollow cylinder with one endbeing closed) rather than a film. The endoscope distal end 20 t isaccommodated in the inner space of this cap. That is, the cover 10Cincludes a cylindrical attaching portion which covers the lateralsurface of the distal end 20 t when the cover 10C is attached to theendoscope distal end 20 t. It is preferred that the cover member 16 ismade of, for example, the aforementioned elastomer, the cover member 16has elasticity, and the cover member 16 is configured such that astraining force is exerted on the lateral surface of the endoscopedistal end 20 t.

FIG. 4(a), FIG. 4(b) and FIG. 4(c) are schematic cross-sectional viewsof endoscope distal end covers 10D, 10E and 10F, respectively, ofembodiments of the present invention.

Each of the covers 10D and 10E includes a cover film 16 as the covermember 16 and further includes a securing member 18 which includes acylindrical attaching portion capable of pressing the cover member 16against the lateral surface of the endoscope distal end 20 t. Thesecuring member 18 may include a portion capable of pressing theperiphery of the upper surface of the film 14 against the end face ofthe endoscope distal end 20 t. The securing member 18 can be made of,for example, the aforementioned elastomer as is the cover member 16 ofthe cover 10C shown in FIG. 3(c) which includes the cylindricalattaching portion.

The cover 10E shown in FIG. 4(b) includes, in addition to the syntheticpolymer film 13 a provided outside the cover film 16, another syntheticpolymer film 13 b provided on the endoscope 20 side of the cover member16. The synthetic polymer films 13 a, 13 b each have the sameconfiguration as the above-described synthetic polymer film and areformed on the base film 12 a, 12 b using, for example, a UV-curableresin. The base film 12 a, 12 b is adhered to the cover film 16 using,for example, an adhesive layer 15 a, 15 b.

The cover 10E is arranged such that an air layer 19 is formed betweenthe synthetic polymer film 13 b and the endoscope 20 (the distal end 20t). The securing member 18 of the cover 10E can also be made of, forexample, the aforementioned elastomer as is the cover member 16 of thecover 10C shown in FIG. 3(c) which has the cylindrical attachingportion. The position of the cover 10E (the thickness of the air layer19) may be, for example, indicated with a mark (line) in a portion ofthe perimeter of the lateral surface of the cover 10E which is coplanarwith the end face of the distal end 20 t when the cover 10E is attached,or may be indicated with a mark or step in the lateral surface of theendoscope 20. The thickness of the air layer 19 is not particularlysignificant although it is preferred that the synthetic polymer film 13b does not come into contact with the end face of the endoscope 20. Ifthe synthetic polymer film 13 b is in contact with the end face of theendoscope 20, there is a probability that the synthetic polymer film 13b will not sufficiently perform an antireflection function.

If an air layer is formed between the cover film 16 and the end face ofthe endoscope 20 when the cover 10D shown in FIG. 4(a) is attached tothe endoscope 20, the amount of light to be guided to the observationwindow reduces due to reflection. In contrast, when the cover 10E shownin FIG. 4(b) is used, the loss of light is suppressed to a small amounteven if an air layer is formed because the synthetic polymer film 13 bfunctions as an antireflection film.

The securing member 18 is preferably configured so as not to easily falloff from the endoscope distal end 20 t in order that, when inserted orpulled out through a trocar, part of the securing member 18 is preventedfrom being caught by the trocar and remaining in a body cavity. Forexample, likewise as in the cover 10D shown in FIG. 4(a), the securingmember 18 can be configured so as to thinly cover the entirety of theendoscope 20 in the longitudinal direction of the endoscope 20, so thata smaller part of the securing member 18 can be caught by the trocar orthe like. However, the securing member 18 is not limited to thisexample. So long as the cover member 16 is assuredly secured, part ofthe cover member 16 may be secured using a medical tape as the securingmember 18 likewise as in the cover 10F shown in FIG. 4(c). Other thanthe medical tape, a cord or rubber may be used as the securing member 18for securing. The securing member 18 may be a member which isstretchable like rubber, or may be a fastening device such as screw,hook, etc., provided between the endoscope distal end 20 t and the covermember 16.

FIG. 5 shows schematic cross-sectional views showing states of theendoscope distal end cover 10C of an embodiment of the present inventionand an attachment 22 attached thereto.

In attaching the cover 10C that has the cover film to the endoscopedistal end 20 t, for example, an attachment 22 for securing the field ofview (space) for observation may be used instead of the above-describedsecuring member 18. An attachment 22 which is made of a transparentelastomer is commercially available. The cover film 16 may be adhered tothe endoscope distal end 20 t using an adhesive agent as describedabove. Alternatively, the cover film 16 may not be adhered to theendoscope distal end 20 t. For example, as shown in FIG. 5(b), the coverfilm 16 may be attached to the distal end of the attachment 22. Adheringthe cover film 16 to the attachment 22 via the adhesive layer 15 issometimes preferred rather than adhering the cover film 16 to theendoscope distal end 20 t because the risk of forming scratches andsmears on the observation window of the endoscope 20 decreases. Theattachment 22 is secured to the distal end 20 t using, for example, astretchable medical tape.

The above-described methods for securing the endoscope distal end covercan be appropriately employed in combination. A configuration wheresynthetic polymer films are provided on opposite sides can be combinedwith the previously-illustrated structure.

Next, schematic diagrams showing an end face of the distal end ofendoscopes 20A, 20B and 20C of an embodiment of the present inventionare shown in FIG. 6(a) through FIG. 6(c). The above-described endoscopedistal end covers are applicable to any of the endoscopes.

The endoscope 20A shown in FIG. 6(a) has, at the end face of the distalend 20 t, an observation window 32, illumination windows 34 a, 34 b, aforceps opening 36 and an ejection nozzle 38. The observation window 32is washed by spraying a washer liquid and/or compressed air from theejection nozzle 38 against the observation window 32.

The endoscope distal end cover 10F has an opening 10Fa through which theforceps opening 36 and the ejection nozzle 38 are exposed. The otherfeatures of the endoscope distal end cover 10F are the same as those ofany of the above-described covers.

The surface of the cover 10F has a moth-eye structure of the syntheticpolymer film 13 and has excellent water repellency and excellent oilrepellency so that a body fluid, blood or the like is unlikely to adhereto the surface. Even if a body fluid, blood or the like adheres to thesurface, it will be easily removed by a washer liquid and/or compressedair from the ejection nozzle 38 and, therefore, the surfaces of theobservation window 32 and the illumination windows 34 a, 34 b can bekept clean.

The endoscope 20B shown in FIG. 6(b) does not have an ejection nozzle.Therefore, the endoscope distal end cover 10G has an opening 10Gathrough which the forceps opening 36 is exposed. The other features ofthe endoscope distal end cover 10G are the same as those of any of theabove-described covers. Since the cover 10G has excellent waterrepellency and excellent oil repellency, a body fluid, blood or the likeis unlikely to adhere to the cover 10G and, thus, it is not necessary towash the cover 10G. By omitting the mechanism for washing, the endoscope20B can have a smaller size than the endoscope 20A.

The endoscope 20C shown in FIG. 6(c) has only an observation window 32and illumination windows 34 a, 34 b at the end face of the distal end 20t. Therefore, the endoscope distal end cover 10H does not have anopening and is arranged so as to cover the entirety of the end face ofthe distal end 20 t.

As a matter of course, an endoscope of an embodiment of the presentinvention is not limited to those illustrated in this specification butcan be variously modified.

[Liquid Film of Water-Repellent Oil Covering Surface of SyntheticPolymer Film]

In the endoscope distal end cover of the above-described embodiment, aliquid film of a water-repellent oil covering at least a portion of thesynthetic polymer film located above the observation window is furtherprovided, whereby the effect of suppressing adhesion of blood or bodyfluid to the observation window of the endoscope can be furtherimproved, and the durability of the blood adhesion suppressing effectcan be improved.

As the water-repellent oil, a silicone oil or a fluoric oil can suitablybe used. As the silicone oil, a non-reactive silicone oil is preferred.For example, a dimethyl silicone oil (dimethyl siloxane with methylgroups at all of the side chains and termini) can be suitably used. Themethod of applying the water-repellent oil to the surface of thesynthetic polymer film is not particularly limited, and knownapplication methods are broadly applicable.

FIG. 7(a), FIG. 7(b) and FIG. 7(c) schematically show states where thewater-repellent oil is applied to the surface of the film 14A shown inFIG. 2(a). As a matter of course, the present invention is not limitedto these examples. The water-repellent oil may be applied to the surfaceof the film 14B shown in FIG. 2(b).

As in a film 14Asa shown in FIG. 7(a), the space between a plurality ofraised portions 13Ap at the surface of the synthetic polymer film 13A ispartially filled with a water-repellent oil 62A. Specifically, thesurface of the water-repellent oil 62A may be lower than the pluralityof raised portions 13Ap such that the tip ends of the plurality ofraised portions 13Ap are projected above the surface of thewater-repellent oil 62A. Alternatively, as in a film 14Asb shown in FIG.7(b), a water-repellent oil 62B may be applied so as to cover theentirety of the plurality of raised portions 13Ap. Specifically, thesurface of the water-repellent oil 62B may be higher than the pluralityof raised portions 13Ap such that the tip ends of the plurality ofraised portions 13Ap are present inside the layer of the water-repellentoil 62B.

When the water-repellent oil 62B covers the entirety of the plurality ofraised portions 13Ap as in the film 14Asb shown in FIG. 7(b), theantireflection function of the plurality of raised portions 13Ap islost. On the other hand, in the film 14Asa shown in FIG. 7(a), the tipends of the plurality of raised portions 13Ap are projected above thesurface of the water-repellent oil 62A and, therefore, theantireflection function is remained. Thus, whether the configurationthat results after application of the water-repellent oil to themoth-eye surface is like the film 14Asa shown in FIG. 7(a) or the film14Asb shown in FIG. 7(b) can be determined by observing with an eye thedegree of surface reflection.

Still alternatively, as in a film 14Asc shown in FIG. 7(c), awater-repellent and oil-repellent layer 13F may be formed at the surfaceof the synthetic polymer film 13A, and the water-repellent oil 62A maybe applied to the moth-eye surface that has the water-repellent andoil-repellent layer 13F. In the example described herein, the spacebetween the plurality of raised portions 13Ap at the surface of thesynthetic polymer film 13A is partially filled with the water-repellentoil 62A likewise as in the film 14Asa of FIG. 7(a), although thewater-repellent oil 62B may be applied so as to cover the entirety ofthe plurality of raised portions 13Ap likewise as in the film 14Asb ofFIG. 7(b).

When the water-repellent and oil-repellent layer 13F is formed at themoth-eye surface of the synthetic polymer film 13A as will be describedlater with experimental examples, the synthetic polymer film 13A may behydrophilic. As a matter of course, from the viewpoint of stability orthe like, it is preferred that the synthetic polymer film 13A has waterrepellency. The water-repellent and oil-repellent layer 13F can beformed using, for example, a fluoric coating material. A preferredthickness of the water-repellent and oil-repellent layer 13F is, forexample, not less than 1 nm and not more than 50 nm, although it dependson whether the underlying synthetic polymer film 13A is hydrophilic orwater-repellent and on the degree of hydrophilicity or water repellency.

The surface of the synthetic polymer film of the endoscope distal endcover of the above-described embodiment has excellent water repellencyand excellent oil repellency, where the static contact angle of water(at the lapse of 10 seconds since the landing of the drop) with respectto the surface is not less than 128°, preferably not less than 150°, andthe static contact angle of hexadecane (at the lapse of 10 seconds sincethe landing of the drop) with respect to the surface is not less than35°, preferably not less than 60°. That is, a synthetic polymer filmwith the moth-eye surface where the static contact angle of water withrespect to the surface is not less than 128° and the static contactangle of hexadecane with respect to the surface is not less than 35° canitself be used for the endoscope distal end cover, although in thepresent embodiment the water repellency and the oil repellency requiredfor the surface of the synthetic polymer film may be lower than thoserequired for the synthetic polymer film of the previously-describedembodiment because the water-repellent oil is applied to the surface.Specifically, when a liquid film of the water-repellent oil is formed,the surface of the synthetic polymer film only needs the static contactangle of water (at the lapse of 10 seconds since the landing of thedrop) to be not less than about 98° (more than 99°), and it ispreferably not less than 103°. As a matter of course, as in thesynthetic polymer films of the previously-described embodiment, it ispreferred that the effect on the pH of water (aqueous solution) adheredto the surface is small. Thus, when the synthetic polymer film is formedusing a photocurable resin, it is preferred to use the above-describedpolymerization initiators which does not produce an organic acid.

Hereinafter, as will be described with experimental examples, thewater-repellent oil is preferably a silicone oil whose kinematicviscosity is lower than 350 mm²/s (1 mm²/s=1 cSt), more preferably asilicone oil whose kinematic viscosity is equal to or lower than 10mm²/s. In the description of the experimental examples which will beprovided below, for the sake of distinguishment from Examples andComparative Examples of the previously-described embodiment, “Example2-” and “Comparative Example 2-” are prefixed and used only forcomparison in the forms where the water-repellent oil was applied to themoth-eye surface. Therefore, even if a synthetic polymer film of anexample of the previously-described embodiment is included, it can bereferred to as “Comparative Example” in the following description. Onthe contrary, even if a synthetic polymer film of a comparative examplein the description of the previously-described embodiment is included,it can be referred to as “Example” in the following description.

In the following experimental examples, the water-repellent materialsused were the UV-curable resin of Example 2 described above (referred toas Water Repellency 2) and the water-repellent materials of Examples 2A,2B and 2C shown in TABLE 5B (Water Repellency 2A, 2B, 2C), and thehydrophilic materials used were the UV-curable resin of ComparativeExample 2 described above (referred to as Hydrophilicity 1) and thehydrophilic materials (Hydrophilicity 2, 3, 4) whose compositions areshown in TABLE 8. Source materials of the UV-curable resins ofHydrophilicity 2, 3, 4 are shown in TABLE 1 and TABLE 9. AdditivePC-3662 is an antistatic agent manufactured by Marubishi Oil ChemicalCorporation, which is a silicone oil containing lithium salts. Thecontact angles of the surfaces of the synthetic polymer films which weremade of the UV-curable resins of Hydrophilicity 2, 3, 4 with respect towater (at the lapse of 1 second and 10 seconds since the landing of thedrop) are shown in TABLE 10.

TABLE 8 Monomer Initiator Additive ND-DA PE300 4HBA ATMM3LMN 819 TPOPC-3662 Hydrophilicity 2 79.2% — — 20.3% 0.5% — — Hydrophilicity 3 —78.8% — 20.7% 0.5% — — Hydrophilicity 4 — — 46.3% 46.3% 1.4% 1.4% 4.6%

TABLE 9 Product Name Manufacturer Name Compound Name ND-DA ND-DA DKS Co.Ltd. 1,9-nonanediol diacrylate PE300 PE-300 DKS Co. Ltd. polyethyleneglycol (300) diacrylate 4HBA 4HBA Nihon Kasei Co. Ltd. 4-hydroxybutylacrylate

TABLE 10 Water Contact Angle Film (°) Resin Surface Shape 1 sec 10 secComparative Hydrophilicity 2 moth-eye 97.2 81.5 Example 2-6 ComparativeHydrophilicity 3 moth-eye 49.9 49.3 Example 2-7 ComparativeHydrophilicity 4 moth-eye 36.7 35.4 Example 2-8

Using these water-repellent or hydrophilic materials, sample films whichhad at the surface the moth-eye structure schematically shown in FIG.2(a) (D_(p) was about 200 nm, D_(int) was about 200 nm, D_(h) was about150 nm) were produced by the previously-described method.

Also, another sample film was produced which had a water-repellent andoil-repellent layer 13F at the surface of the synthetic polymer film 13Alikewise as in the film 14Asc shown in FIG. 7(c). Herein, syntheticpolymer films were produced using a hydrophilic material(Hydrophilicity 1) in the same way as that described above, andthereafter, sample films of Comparative Example 2-12 and Example 2-14were produced as follows.

Comparative Example 2-12: a fluoric coating material with theconcentration of 0.01 mass % (FluoroSurf (registered trademark)manufactured by Fluoro Technology) was poured over a surface of ahydrophilic synthetic polymer film. Thereafter, the film was dried atroom temperature for about one hour. Then, the above-described dilutedfluoric coating material was poured over the entire surface, and thefilm was further kept at room temperature for about three hours(Hydrophilic 1Fd). That is, the diluted fluoric coating material wasapplied twice.

Example 2-14: The sample film was produced in the same way asComparative Example 2-12 except that the concentration of the fluoriccoating material was 0.1 mass % (Hydrophilic 1Fc).

The results of measurement of the contact angle of water with respect tothe respective sample films are shown in TABLE 11.

TABLE 11 Film Water Contact Angle Surface (°) Resin Shape 1 sec 10 secComparative Hydrophilicity 1Fd moth-eye 83.2 71.4 Example 2-12 Example2-14 Hydrophilicity 1Fc moth-eye 115 103.1

As the water-repellent oil, three types of dimethyl silicone oils whosekinematic viscosity was 10 mm²/s, 350 mm²/s and 500 mm²/s (KF-96-10cs,KF-96-350cs and KF-96-500cs manufactured by Shin-Etsu Chemical Co.,Ltd.) were used.

The aforementioned silicone oils were applied to the surface of thesample films (synthetic polymer films) by any of the following threemethods.

First, the sample film was adhered onto a raw glass plate using anadhesive agent such that the surface of the sample film was flat.

Then, drops of several mL of the silicone oil was placed on the surfaceof the sample film, and the glass plate was spun by a spinner at apredetermined rotational speed (200 rpm, 1000 rpm or 3500 rpm) for 12seconds (Method 1: Spin coating method).

The silicone oil was poured over the entire surface of the sample filmwhile the surface of the sample film adhered onto the raw glass platewas kept at 45° with respect to a horizontal direction, and then thesample film was left for 30 minutes (Method 2: Pour-over method).

The entire surface of the sample film adhered onto the raw glass platewas wiped with cloth soaked with the silicone oil (for example, wipingcloth which can be suitably used in a clean room (herein, Savina(registered trademark) manufactured by KB SEIREN, LTD. was used))(Method 3: Cloth wiping method).

The sample films prepared as described above and the raw glass plate(see TABLE 12 below) were evaluated as to the blood adhesion suppressingeffect and its durability as will be described below. Herein also, sheepblood (whole blood) was used instead of human blood as in the experimentfor the previously-described embodiment.

Three types of tests described below were carried out.

(Test 1)

Each film was placed such that the surface faces upward with a slant ofabout 20°-30°. Six 20 μL drops of sheep whole blood were dropped fromabove the film, and it was checked whether the blood flowed down to thelower part of the film or stayed on the surface of the film.

(Test 2)

After TEST 1 was carried out, 2 mL PBS (phosphate buffered saline) waspoured twice over the entire surface of a film with remaining blood, andit was checked whether or not the blood was washed away.

(Test 3)

After TEST 2 was carried out, TEST 1 was carried out again.

The blood adhesion suppressing effect and its durability were evaluatedbased on the following criteria. When in TEST 1 the blood dropped on thefilm surface flowed down to the lower part of the film, the bloodadhesion suppressing effect was evaluated as being ⊚ (excellent). Whentwo or less blood drops were adhered to the film surface in TEST 1 buteasily washed away in TEST 2, the blood adhesion suppressing effect wasevaluated as being ◯ (good). When more than two blood drops were adheredto the film surface in TEST 1 but easily washed away in TEST 2, theblood adhesion suppressing effect was evaluated as being Δ (tolerable);otherwise, the blood adhesion suppressing effect was evaluated as beingx (not tolerable). The durability of the blood adhesion suppressingeffect was evaluated as being (excellent) when the blood adhesionsuppressing effect achieved as a result of TEST 3 was equivalent to theblood adhesion suppressing effect achieved in TEST 1. When the achievedblood adhesion suppressing effect was equivalent to that of TEST 1although a puddle or the like was found in the washing of TEST 2, thedurability of the blood adhesion suppressing effect was evaluated asbeing ◯ (good). When the achieved blood adhesion suppressing effect wasequivalent to that of TEST 1 except for a location of adhered blood inTEST 1 where the blood adhesion suppressing effect was eliminated (ahistory of blood adhesion remains), the durability of the blood adhesionsuppressing effect was evaluated as being Δ (tolerable). When there wasno blood adhesion suppressing effect or the blood adhesion suppressingeffect was eliminated, the durability of the blood adhesion suppressingeffect was evaluated as being x (not tolerable).

The evaluation results of the blood adhesion suppressing effect and itsdurability are shown in TABLE 12, and the observation results in TEST 1,TEST 2 and TEST 3 are shown in TABLE 13 and TABLE 14.

TABLE 12 Blood Adhesion Surface Silicone Application SuppressingDurability Base Shape Oil Method Effect of Effect Comparative Raw Glassflat none — X X Example 2-1 Comparative Raw Glass flat 10 mm²/s 1000rpm/12 sec ◯ X Example 2-2 Comparative Raw Glass flat 10 mm²/s Pour-over◯ X Example 2-3 Comparative Hydrophilicity 1 moth-eye none — Δ X Example2-4 Comparative Hydrophilicity 1 moth-eye 10 mm²/s 1000 rpm/12 sec ◯ XExample 2-5 Comparative Hydrophilicity 2 moth-eye 10 mm²/s 1000 rpm/12sec ◯ X Example 2-6 Comparative Hydrophilicity 3 moth-eye 10 mm²/s 1000rpm/12 sec ◯ X Example 2-7 Comparative Hydrophilicity 4 moth-eye 10mm²/s 1000 rpm/12 sec ◯ X Example 2-8 Comparative Water Repellency 2flat 10 mm²/s 1000 rpm/12 sec X X Example 2-9 Comparative WaterRepellency 2 flat 10 mm²/s Pour-over X X Example 2-10 Comparative WaterRepellency 2 moth-eye none — ◯ Δ Example 2-11 Comparative Hydrophilicity1Fd moth-eye 10 mm²/s Pour-over X X Example 2-12 Comparative WaterRepellency 2C moth-eye 10 mm²/s 1000 rpm/12 sec X Δ Example 2-13Comparative Water Repellency 2C moth-eye 10 mm²/s Cloth Wiping X ΔExample 2-14 Example 2-1 Water Repellency 2 moth-eye 10 mm²/s 1000rpm/12 sec ⊚ ⊚ Example 2-2 Water Repellency 2 moth-eye 10 mm²/sPour-over ◯ ⊚ Example 2-3 Water Repellency 2 moth-eye 10 mm²/s  200rpm/12 sec ⊚ ⊚ Example 2-4 Water Repellency 2 moth-eye 10 mm²/s 3500rpm/12 sec ⊚ ⊚ Example 2-5 Water Repellency 2 moth-eye 350 mm²/s 1000rpm/12 sec Δ ◯ Example 2-6 Water Repellency 2 moth-eye 350 mm²/sPour-over Δ ◯ Example 2-7 Water Repellency 2 moth-eye 500 mm²/s 1000rpm/12 sec Δ ◯ Example 2-8 Water Repellency 2 moth-eye 500 mm²/sPour-over Δ ◯ Example 2-9 Water Repellency 2 moth-eye 10 mm²/s ClothWiping ⊚ ⊚ Example 2-10 Water Repellency 2A moth-eye 10 mm²/s 1000rpm/12 sec ⊚ ⊚ Example 2-11 Water Repellency 2A moth-eye 10 mm²/s ClothWiping ⊚ ⊚ Example 2-12 Water Repellency 2B moth-eye 10 mm²/s 1000rpm/12 sec ◯ ◯ Example 2-13 Water Repellency 2B moth-eye 10 mm²/s ClothWiping ◯ ◯ Example 2-14 Hydrophilicity 1Fc moth-eye 10 mm²/s 1000 rpm/12sec ◯ ◯

TABLE 13 TEST 1 TEST 2 TEST 3 Comparative Blood did not It took time toEquivalent to Example 2-1 roll down. Flow thoroughly TEST 1. markremained. wash away. Comparative 2 drops adhered. Blood easily Bloodmixed with Example 2-2 Blood fall was flowed but water, spread andsomewhat slow. partially blurred. blurred. Comparative 1 drop adhered.Blood easily Blood mixed with Example 2-3 flowed. water, spread andblurred. Comparative Blood did not Blood easily Blood mixed with Example2-4 roll down. Flow flowed. water, spread and mark remained. blurred.Comparative No blood adhered. Blood easily Blood mixed with Example 2-5Blood fall was flowed. water, spread and somewhat slow. blurred.Comparative No blood adhered. Blood easily Blood mixed with Example 2-6Blood fall was flowed. water, spread and somewhat slow. blurred.Comparative No blood adhered. Blood easily Blood mixed with Example 2-7Blood fall was flowed. water, spread and somewhat slow. blurred.Comparative No blood adhered. Blood easily Blood mixed with Example 2-8Blood fall was flowed. water, spread and somewhat slow. blurred.Comparative No blood adhered. Blood easily Blood mixed with Example 2-9Blood fall was flowed. water, spread and somewhat slow. blurred.Comparative No blood adhered. Blood easily Blood mixed with Example 2-10Blood fall was flowed. water, spread and somewhat slow. blurred.Comparative No blood adhered. Blood easily Blood mixed with Example 2-11Blood fall was flowed. water, spread and somewhat slow. blurred.Comparative 1 drop adhered. Washer liquid Blood mixed with Example 2-12Blood fall was remained in water, spread and slow. drops. blurred.Comparative 1 drop adhered. Washer liquid Blood mixed with Example 2-13Blood fall was remained in water, spread and slow. drops. blurred.Comparative 1 drop adhered. Washer liquid Blood mixed with Example 2-14Blood fall was remained in water, spread and slow. drops. blurred.

TABLE 14 TEST 1 TEST 2 TEST 3 Example 2-1 No blood adhered. Washerliquid Equivalent to also cleanly TEST 1. flowed down. Example 2-2 2drops adhered. Blood was easily Equivalent to Blood fall was washedaway, but TEST 1. somewhat slow. washer liquid blurred. Example 2-3 Noblood adhered. Washer liquid Equivalent to also cleanly TEST 1. floweddown. Example 2-4 No blood adhered. Washer liquid Equivalent to alsocleanly TEST 1. flowed down. Example 2-5 1 drop adhered. Washer liquidEquivalent to Blood fall was partially TEST 1. slow. remained in drops.Example 2-6 Blood fall was Washer liquid Equivalent to slow. partiallyTEST 1. remained in drops. Example 2-7 Blood fall was Washer liquidEquivalent to slow. partially TEST 1. remained in drops. Example 2-8Blood fall was Washer liquid Equivalent to slow. partially TEST 1.remained in drops. Example 2-9 No blood adhered. Washer liquidEquivalent to also cleanly TEST 1. flowed down. Example 2-10 No bloodadhered. Washer liquid Equivalent to also cleanly TEST 1. flowed down.Example 2-11 No blood adhered. Washer liquid Equivalent to also cleanlyTEST 1. flowed down. Example 2-12 No blood adhered. Blood was easilyEquivalent to Blood fall was washed away, but TEST 1. somewhat slow.washer liquid blurred. Example 2-13 No blood adhered. Blood was easilyEquivalent to Blood fall was washed away, but TEST 1. somewhat slow.washer liquid blurred. Example 2-14 No blood adhered. Blood was easilyEquivalent to Blood fall was washed away, but TEST 1. somewhat slow.washer liquid blurred.

As seen from the foregoing results (particularly from the evaluationresults of the effect durability shown in TABLE 12), only syntheticpolymer films with the moth-eye structure at the surface which wereproduced using a water-repellent material (Example 2-1 to Example 2-13)and a synthetic polymer film with the moth-eye structure at the surfacewhich was produced using a hydrophilic material and which had awater-repellent and oil-repellent layer of a sufficient thickness on theresin film (Example 2-14) are excellent in durability of the bloodadhesion suppressing effect. That is, when a silicone oil is applied toa surface but the surface is hydrophilic, the blood adhesion suppressingeffect would not last even though the surface has the moth-eyestructure. This is probably because, during the washing, water entersbetween the surface of the synthetic polymer film and the silicone oil,and the silicone oil is washed away from the surface. It is estimatedthat the surface with the moth-eye structure which is made of awater-repellent material stably holds the silicone oil, and this effectof the water-repellent moth-eye surface is not marred by water usedduring the washing.

The water repellency of the surface of the synthetic polymer film withthe silicone oil provided at the surface (for example, a surface of aresin film (water-repellent) which is made of a photocurable resin or asurface of a water-repellent and oil-repellent layer formed on a resinfilm which is made of a photocurable resin (the film may also behydrophilic)) only requires that the static contact angle of water (atthe lapse of 10 seconds since the landing of the drop) is not less thanabout 98° (more than 99°). This is supported by the results of Example2-12 (Example 2B (Water Repellency 2B) in TABLE 5B).

As understood from the comparison between Example 2-14 and ComparativeExample 2-12, the water-repellent moth-eye surface can also be realizedby forming a water-repellent and oil-repellent layer of a sufficientthickness on the moth-eye surface of a synthetic polymer film which ismade of a hydrophilic material. Preferably, the thickness of thewater-repellent and oil-repellent layer is, for example, not less than 5nm. The static contact angle of water (at the lapse of 10 seconds sincethe landing of the drop) is preferably not less than 103° (see TABLE11).

Comparing Example 2-1 to Example 2-14, it can be said that the siliconeoil preferably has a lower kinematic viscosity. Example 2-1 to Example2-4 and Example 2-9 to Example 2-14 in which the kinematic viscosity ofthe silicone oil used was 10 mm²/s exhibited better durability in theblood adhesion suppressing effect than Example 2-5 to Example 2-8 inwhich the kinematic viscosity of the silicone oil used was equal to orhigher than 350 mm²/s. Therefore, it can be said that a silicone oilwhich has at least a kinematic viscosity of lower than 350 mm²/s ispreferred, and a silicone oil which has at least a kinematic viscosityequal to or lower than 10 mm²/s is more preferred. This is probablybecause the structure shown in FIG. 7(a) is more likely to be realizedas the kinematic viscosity decreases, and the structure shown in FIG.7(b) is more likely to be realized as the kinematic viscosity increases.That is, it is estimated that the effect of improving the water and oilrepellency which is achieved by the moth-eye structure contributes tothe structure shown in FIG. 7(a). As for the method of applying thesilicone oil to the surface, no difference was found among Method 1 toMethod 3, and any of the methods which is convenient in clinicalworkplaces or the like can be employed.

Next, the evaluation results of the antifog property of the sample filmsare described. When an endoscope is inserted into a body, dewcondensation forms sometimes. This is because both temperature andhumidity are higher inside the body than an operating room that isusually regulated to a relatively low temperature. As a matter ofcourse, preferably, the endoscope distal end cover can suppress thistype of dew condensation.

As the sample films, the above-described sample films (Example 2-1,Comparative Example 2-11, Comparative Example 2-4, Comparative Example2-5) were used.

According to the test method employed herein, the respective samplefilms were left in a pre-test environment at a low temperature and a lowhumidity for one hour or longer so as to be sufficiently acclimated tothe environment. Thereafter, within 10 seconds, each of the sample filmswas put into a test environment at a high temperature and a highhumidity, and the state of dew condensation at the surface of the samplefilm (antifog property) was observed with an eye. The results are shownin TABLE 15. In TABLE 15, ⊚: not fogged, Δ: slightly fogged, x: fogged(water drops formed), xx: wet (water drops formed over the entiresurface).

TABLE 15 Pre-test Environment 5° C./10% RH 5° C./10% RH Test Environment30° C./85% RH 25° C./50% RH Silicone Oil Provided Not provided ProvidedNot provided Material PET X X X X Water ◯ Δ ◯ ◯ Repellency 2 Example 2-1Comparative Example 2-1 Comparative Example 2-11 Example 2-11Hydrophilicity 1 XX XX ◯ ◯ Comparative Comparative ComparativeComparative Example 2-5 Example 2-4 Example 2-5 Example 2-4

In a test environment at 25° C./50% RH, the presence/absence of siliconeresulted in no difference between the hydrophilic moth-eye and thewater-repellent moth-eye. In a test environment at 30° C./85% RH whichis closer to the environment inside the body, formation of dewcondensation occurred at the surface of the sample film with thehydrophilic moth-eye so that the entire surface was wet, while no fogoccurred in an example where the surface of the water-repellent moth-eyewas provided with the silicone oil. When the silicone oil was notapplied to the surface of the water-repellent moth-eye, the surface wasslightly fogged. It is thus concluded that the effect of preventing dewcondensation was improved by applying the silicone oil to thewater-repellent moth-eye surface. As seen from this result, from theviewpoint of antifog property, it is preferred to use thewater-repellent moth-eye. It is estimated that the difference in theabove-described results between the water-repellent moth-eye and thehydrophilic moth-eye with the silicone oil applied to the surface isattributed to the state where the moth-eye structure is not thoroughlyfilled with the silicone oil (the state shown in FIG. 7(a)).

INDUSTRIAL APPLICABILITY

An endoscope distal end cover and an endoscope of an embodiment of thepresent invention are capable of suppressing adhesion of blood or bodyfluid to an observation window and easily securing the visual field forobservation.

REFERENCE SIGNS LIST

-   10, 10A-10G: endoscope distal end cover-   12, 12A, 12B: base film-   13, 13A, 13B: synthetic polymer film-   13Ap, 13Bp: raised portion-   14, 14A, 14B, 14Asa, 14Asb, 14Asc: film-   15, 15 a, 15 b: adhesive layer-   16: cover member-   17: adhesive layer-   19: air layer-   18: securing member-   20 t: distal end-   20, 20A, 20B, 20C: endoscope-   20 a: insertion section-   20 b: control section-   22: attachment-   32: observation window-   34 a, 34 b: illumination window-   36: forceps opening-   38: ejection nozzle-   42: trocar-   44: valve-   54: liquid supply tube-   62A, 62B: water-repellent oil-   100: endoscope system

1. An endoscope distal end cover for protecting a distal end of anendoscope which has an observation window at the distal end, comprising:a synthetic polymer film which is to be located over the observationwindow when the endoscope distal end cover is attached to the distal endof the endoscope, wherein the synthetic polymer film has a surface whichincludes a plurality of raised portions, when viewed in a normaldirection of the synthetic polymer film, a two-dimensional size of theplurality of raised portions is in the range of more than 20 nm and lessthan 500 nm, and a static contact angle of water with respect to thesurface is not less than 98°.
 2. The endoscope distal end cover of claim1, wherein the static contact angle of water with respect to the surfaceof the synthetic polymer film is not less than 128°.
 3. The endoscopedistal end cover of claim 1, further comprising a liquid film of awater-repellent oil covering a surface of at least a portion of thesynthetic polymer film located on the observation window.
 4. Theendoscope distal end cover of claim 3, wherein the water-repellent oilis a silicone oil or a fluoric oil.
 5. The endoscope distal end cover ofclaim 3, wherein the water-repellent oil is a silicone oil whosekinematic viscosity is lower than 350 mm²/s.
 6. The endoscope distal endcover of claim 3, or wherein the water-repellent oil is a silicone oilwhose kinematic viscosity is equal to or lower than 10 mm²/s.
 7. Theendoscope distal end cover of claim 1, wherein the synthetic polymerfilm includes a resin film which is made of a photocurable resin.
 8. Theendoscope distal end cover of claim 7, wherein the synthetic polymerfilm further includes a water-repellent and oil-repellent layer formedon the resin film.
 9. The endoscope distal end cover of claim 7, whereinthe photocurable resin contains a first polymerizable fluoric compoundwhich contains a fluorine element, the first polymerizable fluoriccompound has a plurality of polymerizable functional groups and has amolecular weight of not less than 1000 and not more than 5000, and atthe lapse of 5 minutes since placing a 200 μL drop of water on thesurface of the synthetic polymer film, a pH of an aqueous solution isnot less than 6.5 and not more than 7.5.
 10. The endoscope distal endcover of claim 9, wherein the photocurable resin contains aphotopolymerization initiator, and the photopolymerization initiatorcontains at least one of the group consisting of ethanone,1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl]-,1-(O-acetyloxime),2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]phenyl}-2-methyl-propan-1-one,and 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propane-1-one.11. The endoscope distal end cover of claim 9 or 10, wherein thephotocurable resin further contains a second polymerizable fluoriccompound which contains a fluorine element, and the second polymerizablefluoric compound is a monofunctional polymerizable compound and has amolecular weight of not less than 100 and not more than
 1000. 12. Theendoscope distal end cover of claim 9, wherein a proportion of the firstpolymerizable fluoric compound to the photocurable resin is not lessthan 1 mass % and not more than 5 mass %.
 13. An endoscope comprisingthe endoscope distal end cover as set forth in claim 1, the endoscopedistal end cover being attached to the endoscope.